One of the most common deficiencies with high performance wetting agents comprised of alkoxylated organosilicone surfactants is that foam generated from these products is difficult to control. Organosilicone surfactants, especially trisiloxane alkoxylates (TSA), are able to reduce the aqueous surface tension of spray solutions to values below 21 mN/m. At these low values it is difficult for conventional foam control agents, such as, polydimethylsiloxanes (PDMS), to spread at the liquid/air interface, because the bulk surface tension of these foam control agents is similar to the aqueous surface tension of these organosilicone surfactants.
In a related publication, EP 0046342 discloses the use of an antifoam in a detergent composition containing a PDMS, and a silicone-polyoxyalkylene copolymer ("Copolymer"). The Copolymer therein is a spreading agent for the defoamer composition, not a defoamer. U.S. Pat. No. 4,514,319 to Kulkarni et al. also describes the use of a Copolymer as a component in an antifoam composition as a spreading agent and an emulsifier, but not as a foam control agent ("FCA").
EP 0 791 384 to Policello discloses adding a second silicone to the TSA to lower the foaming of the TSA, however such combinations do not provide optimal foam control and maintain superspreading.